2.The Readiness Status is the product of a combination of two elements—technology and market.
i.Technological readiness, the first criterion, is a measure of product maturation. What this means for the EVs considered for connecting to and supporting the electrical grid, is the level to which VGI EV technology is ready for but may differ between EV types.
ii.Technological readiness measures the technology in its current capabilities, while the second criterion—market adoption and existing market conditions—measures it based on the market. This criterion seeks to measure the existing adoption of EV types and the potential for their market growth. This takes into consideration existing market conditions, more specifically, consumer interest and demand for VGI EVs.
3.The last perspective is the Likelihood of Owner Participation, which is influenced by two criterions.
i.The first criterion analyzes the incentives and benefits for owners who participate in bi-directional grid support programs, as well as existing and planned incentives for transmission and distribution construction.
ii.The second criterion is the likelihood of an owner’s willingness to invest in bi-directional charging equipment that is likely needed to implement wide-scale VGI EV infrastructure.
1.5.Relevant application alternatives
As we assessed the technologies/products in question, certain options were deemed unlikely to help utilities serve summer peak needs, although we did see opportunities for these options to serve other service requirements, for example, ancillary services, renewables integration, volt/VAR support, etc. Municipal buses, for example, were likely to be in use during summer peak hours, but they could also be very helpful in integrating wind power at night (off-peak hours). Police fleets were cut from the list because emergency responders would likely need to keep their SoCs as high as possible, but they could also support ancillary services while plugged in. Taxi fleets were a mismatch in the same way as municipal buses, but could also help with renewables integration. Delivery fleets were cut from the list for the same reason, although some types of delivery fleets could provide some export power if they finished their routes early enough in the day.
High-speed charging equipment (especially on-route chargers backed up with stationary storage batteries) might offer some potential for program participation; however, we determined that it would be best to include them with their corresponding fleets and not treat them as a stand-alone option. While off-road EVs offered promise, the most significant potential involved the use of large-load vehicles associated with airports and seaports (e.g., tugs, ferries, cranes, electric rail, etc.). However, these technologies/products are still being developed and tested in early pilots and demonstrations. After performing the gap analysis, we were left with five application alternatives—municipal non-bus fleets, school bus fleets, military fleets, garbage truck fleets and individually owned EVs.
2.Municipal Non-Bus and Non-Emergency Fleets
More and more municipalities and cities are beginning to electrify their fleets, as moving towards EVs can help reduce emissions, lead to better public health and lower government spending [7]. Municipal non-bus fleets include a whole host of vehicles that cities use every day, from sanitation inspections to water meter readings and building inspections. Most non-bus fleets are made up of the same make and model that individuals can purchase for everyday use. While these are much smaller than a city bus, for example, a large city would have a number of smaller EVs as part of the fleet.
A key factor in the selection of non-bus fleets as an alternative for study was their immediate market availability, as well as their availability to be plugged in and ready during peak periods. Assume a 2019 Nissan Leaf as a case example of a municipal fleet vehicle: the Leaf has a maximum range of 150 miles [8], which can more than accommodate the average daily needs to fulfill municipality duties and still have an available SoC for the 4 pm peak hour. Additionally, since the Leaf has the ability to quick charge up to 90 miles in 30 minutes via a DC quickcharger, it can still be drawn down to a low SoC and then quickly charged again once the peak ends and still be ready to resume duties the following morning.
3.School Bus Fleets
School buses were selected for their large stored potential energy, as well as for their significant downtime during the summer months. As school buses normally sit idle during the summer months, they would be able to support a peak V2G program with a larger portion of their SoC. As a whole, the school bus system is the largest form of public transportation system in the country [9]. With more than 480,000 buses in service across the United States, an entire electric fleet capable of V2G interconnection could be a very attractive alternative.
However, only a fraction of the over 480,000 available school buses are electric, as of 2018 [10]. The largest barrier to entry is the significant cost associated with electric models; a full electric school bus typically costs three times a conventional diesel or propane model. Even so, some school districts are beginning to convert or supplement their fleets with electric models. For example, the White Plains of the New York School District, in partnership with their bus contractor—National Express and Con Edison—has purchased five Lion Electric bus models, each with a battery capacity of 88 kWh [11], specifically with V2G in mind. As part of the agreement, Con Edison contributed US$100,000 [10, 12] towards the purchase of each bus and plans to use all five buses during summer peak periods, which will provide an additional 75 kW of energy to the grid [13].
With such pilot programs, we feel that V2G electric school bus integration could be a reality by 2025, especially if more school districts and operators partner with utilities to help offset the initial, higher costs.
4.Garbage Truck Fleets
Like school buses, garbage trucks were selected as a possible alternative due to their flexible operating schedules as well as their potential for adoption. To date, most of the garbage trucks in service across the United States use internal combustion engines fueled with either diesel or Compressed Natural Gas (CNG). However, the segment shows large potential towards electrification, with large, heavy duty trucks (e.g., electrified garbage trucks) that start and stop every 200 feet through the use of regenerative braking. This type of braking can help recover energy consistently [14]. With the use of a regenerative brake system, it is estimated that an electric garbage truck can save up to US$35,000 per year in operating costs when compared to a traditional diesel/CNG model [15].
There are a number of manufacturers that are either building or developing electric garbage truck models, with models currently in use in California. Manufacturers of electric garbage trucks include Chinese Build Your Dreams (BYD), Swedish Volvo and Peterbilt, Mack and Wrightspeed. Battery capacities currently range from 60 to 300 kWh [16, 17].
Depending on its battery
